1. Field of the Invention
This invention relates to an ink jet printer wherein ink drops are selectively jetted toward a recording medium to effect printing, and more particularly to an ink jet printer of the structure wherein an ink cartridge including an ink jet head and an ink tank which are formed as a unit is removably mounted on a carriage.
2. Description of the Related Art
An ink jet printer is already known wherein an ink cartridge including an ink tank and an ink jet head which are formed as a unit is removably mounted on a carriage which is mounted for back and forth translational movement on a body case and ink is jetted from nozzles of the ink jet head during movement of the carriage to effect printing.
In an ink jet printer of the type mentioned, due to the structure that the ink jet head is removably mounted on the carriage on the body case, a structure for electrically connecting a printing control circuit provided on the body case side and the ink jet head to each other is required. According to an exemplary one of such electric connection structures, a connector on the market is mounted on the carriage and connected to the printing control circuit while pin terminals are provided on the ink cartridge and connected to the ink jet head, and when the ink cartridge is mounted onto the carriage, the pin terminals on the ink cartridge side are connected to the connector on the carriage side. The connection structure, however, requires a structure for relative movement between the pin terminals and the connector since it sometimes occurs that, upon mounting of the ink cartridge, the connector must be moved relative to the pin terminals due to an error in assembly of parts. Such structure for relative movement complicates the structure of the ink jet printer and raises the cost of parts.
Thus, such a connection structure as shown in FIG. 22 has been proposed. In the following, the connection structure will be described with reference to FIG. 22. A rubber pad 101 is carried on a carriage (not shown) mounted for back and forth translational movement on a body case (not shown). A large number of projections 102 are formed on a surface of the rubber pad 101. A flexible cable 103 made of a vinyl chloride material is carried in an opposing relationship to the rubber pad 101 on the carriage. A large number of connection portions 104 are formed from a thin film metal in an opposing relationship to the projections 102 on the flexible cable 103 such that they are swollen toward the surface of the rubber pad 101. The connection portions 104 are connected to a driving section (not shown) by way of connection lines 105 formed on the flexible cable 103. A connection pattern 106 is formed from metal foil on one face of an ink cartridge (not shown) removably carried on the carriage. The connection pattern 106 has a large number of terminals 107 for contacting with the connection portions 104. The terminals 107 are connected to heat generation elements provided in the insides of nozzles (not shown) of the ink jet head.
Accordingly, when the ink cartridge is mounted onto the carriage, the connection portions 104 connected to the driving section are connected to the terminals 107 of the ink jet head. Here, since the projection heights of the connection portions 104 are not uniform and they do not contact fully with the terminals 107, the connection portions 104 are pressed against the terminals 107 by the projections 102 of the rubber pad 101. Upon printing, a voltage is applied to a selected one or ones of the terminals 107 to cause the heat generation element or elements connected to the selected terminal or terminals 7 to boil ink in the nozzle or nozzles, and the ink is jetted from the nozzle or nozzles by the pressure or pressures raised as a result of such boiling. Ink is supplied from an ink tank (not shown) to each of the nozzles.
Problems of the prior art ink jet printer will be described subsequently. As a conventional method of mounting an ink cartridge onto a carriage, a method of positioning and securing an outer shell of the ink cartridge to the carriage is employed commonly. However, with such method, it sometimes occurs that positioning of the ink jet head and nozzles with respect to the ink cartridge is inaccurate or the ink cartridge is displaced out of position when it is mounted onto the carriage, and accordingly, a dispersion is liable to be caused with the positions of the nozzles of the ink jet head with respect to the recording medium. In this instance, ink will not be jetted in the correct direction, and accordingly, there is a problem that the print quality is deteriorated.
Further, where such a structure as shown in FIG. 22 is employed as a structure for electrically connecting a printing control circuit and an ink jet head to each other, since the amount of deformation of the projections 102 of the rubber pad 101 is small, if there is a dispersion with the mounting position of the ink jet head with respect to the carriage, then there is a problem that it is difficult to contact all of the connection portions 104 under pressure with the terminals 107 with certainty. Besides, since the rubber pad 101 is required, the number of parts is great as much and a high cost is required.